Interpretive Summary: Polyphenolic compounds from blueberries are beneficial to humans and animals due to their perceived bioactive and bio-protective effects. However, these compounds present in blueberries cannot be absorbed by the intestinal epithelial tissue in their native form. These compounds must be converted by gut microbes before their utilization. This study evaluated the effect of a diet enriched with blueberries on the metabolic potential of the gastrointestinal microbiota. We identified biological pathways impacted by blueberries. Our study provided insights into microbial conversion of inactive polyphenols to active forms and will help nutritionists to formulate optimal foods and baby formula for a wide range of consumers.

Technical Abstract:
Polyphenols present in lowbush blueberries cannot be absorbed by the intestinal epithelial tissue in their native form. These compounds are catabolized by the gut microbiota before being utilized. The objective of this research is to study the effect of a diet enriched with lowbush blueberries on the gastrointestinal microbiota’s metabolic potential. Nine three-week-old male Sprague Dawley rats were randomly assigned to two groups. The control group (N=4) was placed on control diet and the treatment group (N=5) was fed the same diet with 8% (w/w) lowbush blueberry powder substituting for dextrose. The animals consumed the diets for 6 weeks after which they were sacrificed. Functional profiles and metabolic potential of the colon microbiota in response to dietary alterations were analyzed using deep whole genome sequencing (WGS). Proteins predicted from WGS DNA sequences were assigned to 3,746 COG, 5,577 KEGG, and 4,474 Pfam families. Statistical comparisons of the protein-coding genes revealed significant changes in 25 GO, 186 KEGG, and 20 Pfam protein families representing 2.1%, 3.3%, 0.02% of all hits identified, respectively. A higher abundance in the COG class pertaining to amino acid biosynthesis was detected in the blueberry diet. The impacts blueberry had on the function of the core microbiota pertained to REDOX homeostasis, DNA replication, modification, and repair, metal binding proteins, and amino acid synthesis. This study helps unravel diverse mechanisms of microbial adaptation to blueberries in the diet of mammals.